JPH0320892Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Technical field The present invention relates to a tape recorder, and particularly to a recording/playback switching circuit that switches between recording and playback operations.

(B) Background Art A tape recorder has a recording function for recording signals on a magnetic tape and a playback function for reproducing the signals recorded on the magnetic tape. Tape recorders equipped with such dual functions, particularly cassette-type tape recorders that use tapes called cassettes, generally use a dual-purpose recording/playback magnetic head that performs both recording and playback operations. Tape recorders using such a magnetic head for recording and playback used a multi-circuit switch to switch between recording and playback operations, but recently a switch with a small number of circuits has been used to switch between recording and playback operations. An electronic switching system has been developed using

(c) Purpose of the invention The present invention aims to provide a switching circuit suitable for a recording/playback switching circuit that electronically switches between recording and playback operations.

(d) Embodiment of the invention The illustrated circuit is an embodiment of the recording/playback switching circuit of the invention. In the figure, reference numeral 1 denotes a recording/playback magnetic head which operates as a recording head during a recording operation and as a playback head during a playback operation;
Reference numeral 2 denotes a tape recorder circuit incorporating a reproduction amplifier circuit, a recording amplifier circuit, a main amplifier circuit, a microphone amplifier circuit, etc., and an input terminal 3 into which a recording signal is input, and an output terminal where a reproduction signal or a monitor signal is output. The output terminal 4 is equipped with an output terminal 4. Reference numeral 5 designates a first recording/playback switch which is normally located at the illustrated playback position and is switched to the recording position on the opposite side by a recording operation, and includes a playback side terminal 5 _P , a recording side terminal 5 _R , and a switching slider 5 . It has a common terminal 5 _C connected to _S and power line 6. A first recording/playback switch 7 outputs a control signal in conjunction with switching of the first recording/playback switch 5 to switch the signal path of the front tape recorder circuit 2 into a state for playback operation and a state for recording operation. It is a switching circuit. Reference numeral 8 denotes a second recording/playback changeover switch that is switched in conjunction with the first recording/playback changeover switch 5, and is connected to the playback side terminal _8P , the recording side terminal _8R , the switching slider _8S , and the power supply line 6. Equipped with common terminal _8C . The second recording/playback changeover switch 8 switches the playback side terminal _8P by the changeover slider _8S while the changeover slider _8S is being displaced from the playback position to the recording position or from the recording position to the playback position by a switching operation. This is a switching type switch in which the recording side terminal _8R and the common terminal _8C are short-circuited. 9 is
Controls the operation/non-operation of the reproduction amplifier circuit, the recording amplifier circuit, the microphone amplifier circuit, and the main amplifier circuit that constitute the tape recorder circuit 2, and switches them to a state for reproduction operation and a state for recording operation. A second recording/playback switching circuit 10 is a switching transistor that controls the switching operation of the second recording/playback switching circuit 9, and when it is in a non-conducting state, it is in a state for a playback operation, and when it is in a conducting state, it is in a state for a recording operation. It has the effect of switching to a state for operation. Reference numeral 11 denotes a time constant circuit connected between the recording side terminal _8R of the second recording/playback switch 8 and the ground, and is composed of a first resistor 12, a second resistor 13, and a capacitor 14. 14 is connected so that a charging voltage of 14 is applied to the base of the switching transistor 10 through a resistor 15. 16, the base is connected to the second recording/playback selector switch 8 via a resistor 17.
It is a control transistor that is connected to the playback side terminal _8P and whose emitter is grounded.
Its collector is connected to a connection point A between a first resistor 12 and a second resistor 13 that constitute the time constant circuit 11 .

The present invention is constructed as described above, and its operation will be explained next. First, the case where the first recording/playback switch 5 and the second record/playback switch 8 are in the illustrated playback position will be described. When the first recording/playback switching switch 5 is in the playback position, the signal path of the tape recorder circuit 2 is in a state for playback operation by the control signal from the first recording/playback switching circuit 7. Furthermore, when the second recording/playback switch 8 is in the playback position, no charging current is supplied to the capacitor 14 constituting the time constant circuit 11 , so the switching transistor 10, which is controlled by the charging voltage of the capacitor 14, is disabled. It is in a conductive state. Therefore, in response to the control signal from the second recording/playback switching circuit 9, the amplifier circuit constituting the tape recorder circuit 2 is in a state for performing a playback operation. Recording/playback magnetic head 1
The reproduction signal reproduced by is amplified by the reproduction amplifier circuit and the main amplifier circuit and then output to the output terminal 4. Therefore, the user can listen to the reproduced signal through a speaker or the like connected to the output terminal 4.

The playback operation is performed as described above, but next, a case will be described in which the first recording/playback changeover switch 5 and the second recording/playback changeover switch 8 are in the recording position, which is opposite to the state shown in the figure. When the first recording/playback switching switch 5 is in the recording position, the signal path of the tape recorder circuit 2 is in a state for recording operation by the control signal from the first recording/playback switching circuit 7. When the second recording/playback switch 8 is in the recording position, a charging current flows through the recording side terminal _8R to the capacitor 14 forming the time constant circuit 11 , so that the capacitor 14 is in a charged state. When the capacitor 14 is in a charged state, the switching transistor 10 controlled by its charging voltage is in a conductive state. Therefore, in response to the control signal from the second recording/playback switching circuit 9, the amplifier circuit constituting the tape recorder circuit 2 is in a state for performing a recording operation. The recording signal from the microphone (not shown) input to the input terminal 3 is amplified by the microphone amplifier circuit and the recording amplifier circuit, and then recorded together with the bias signal from the bias oscillator circuit (not shown). The signal is applied to the reproduction magnetic head 1 and recorded on a magnetic tape.

As described above, the reproduction operation and recording operation in this embodiment are performed, but next, the switching operation accompanying the recording operation will be explained. When the user performs a recording operation in the illustrated state, the first recording and playback switch 5 and the second recording and playback switch 8 are switched to the recording side, but the second recording and playback switch 8 is switched in the middle of switching. Connector 8 _S to playback side terminal 8
_P , the recording side terminal _8R and the common terminal _8C are in a short-circuited state. In such a short-circuited state, power is supplied to the time constant circuit 11 through the recording side terminal _8R , but a bias current is supplied to the base of the control transistor 16 through the reproduction side terminal _8P , and the control transistor 16 is in a conductive state. Therefore, the connection point A is grounded and no charging current flows to the capacitor 14. Therefore, the switching transistor 10 is in a non-conductive state, and the second recording/playback switching circuit 8 does not switch to the recording operation state. When a further switching operation is performed from the state in the middle of such switching, the switching slider 8 _S of the second recording/playback switch 8 moves to the recording side terminal 8 _R side, and the playback side terminal 8 _P and the common terminal 8 _C are connected to each other. The short-circuit condition of is released. As a result, the control transistor 16 which was in a conductive state is reversed to a non-conductive state,
Along with this reversal, the charging operation of the capacitor 14 forming the time constant circuit 11 is started. After a predetermined period of time has elapsed, the charged potential of the capacitor 14 rises to a predetermined potential, and the switching transistor 10, which has been in a non-conductive state, is reversed to a conductive state. When the switching transistor 10 is inverted to a conductive state, the amplifier circuit of the tape recorder circuit 2 is brought into a state for recording operation by the second recording/playback switching circuit 9. As explained above, when the recording operation is performed from the playback state, the operation is performed, but when the second recording/playback selector switch 8 is in the middle of switching, the control transistor 16 is turned on, so that the tape recorder circuit 2 The tape recorder circuit 2 is switched to the recording mode after a predetermined period of time after the second recording/playback switch 8 is switched to the recording side. Even if the user presses and holds the recording button between the playback position and the recording position for a long time, the amplifier circuit will not switch to the recording state after the first recording/playback switch 5 switches the signal path to the recording state. A switch will take place.
Since the state of the amplifier circuit is switched to the recording state after switching the signal path in this way, it is possible to suppress as much as possible the noise generated at the time of switching from being recorded on the magnetic tape. In addition, tape recorders are generally configured so that when canceling the recording operation, the lock of the recording button is released by operating the stop button rather than the recording button, so the second recording/playback switch is activated. The switch 8 is not held in a state in the middle of switching, and the switch to the regeneration state is quickly performed.

(E) Application example of the invention In this example, the switching transistor 10
Although an NPN type transistor is used as the control transistor 16, it is of course possible to use a PNP type transistor or other switching elements.

(F) Effect The recording/playback switching circuit of the present invention is a recording/playback switching switch that is switched from the playback position to the recording position by manual operating force during recording operation, and the playback side terminal and the recording side terminal are switched during the switching. A short-circuited short-circuited switching type switch is used, and the signal path switching operation is performed to switch the amplifier circuit to the recording operation state, regardless of the length of the switching operation time of the record button, by utilizing the switching characteristics of the switch. Since this is carried out after the process has been completed, the effect of noise can be suppressed as much as possible. Therefore, the present invention is very effective when applied to a tape recorder configured to electronically perform recording/playback switching operations.

[Brief explanation of the drawing]

The illustrated circuit is an embodiment of the recording/playback switching circuit of the present invention. Explanation of main drawing numbers, 1...Magnetic head for both recording and playback, 2...Tape recorder circuit, 5...1st recording and playback switching switch, 7...1st recording and playback switching circuit, 8...2nd recording and playback Changeover switch, 9...Second recording/playback switching circuit, 10...Switching transistor, 11 ...Time constant circuit, 16...Control transistor.

Claims (1)

[Scope of utility model registration request] In a tape recorder configured to electronically switch between a recording operation and a playback operation, when the recording operation is performed, the playback position is switched to the recording position by manual operation force, and the signal path of the tape recorder circuit is switched from the playback operation state to the recording position. A first recording/playback switch that is switched to an operating state, and a second recording/playback switch that is switched in conjunction with the first recording/playback switch and short-circuits the playback side terminal and the recording side terminal during the switching. a time constant circuit including a capacitor that is charged when the second recording/playback selector switch is in the recording position; and when the charging potential of the capacitor rises above a predetermined value, the amplifier circuit of the tape recorder circuit is activated for playback. a switching circuit for switching from a state to a recording operation state; and a time constant circuit that is in a conductive state when the second recording/playback switch is in the playback position and the playback side terminal and the recording side terminal are short-circuited. It consists of a control transistor that prevents the charging operation of the capacitor that makes up the
Recording of a tape recorder, characterized in that during a recording operation, the signal path of the tape recorder circuit is switched from a playback operation state to a recording operation state, and then an amplifier circuit of the tape recorder circuit is switched from a playback operation state to a recording operation state. Regeneration switching circuit.